981028 The optimal solution to ensure the excellent ...g...The optimal solution to ensure the excellent certification quality of EMI testing 4 GOOD WILL INSTRUMENT CO., LTD. In Fig.3,

The optimal solution to ensure the excellent certification quality of EMI testing

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www.instek.com GOOD WILL INSTRUMENT CO., LTD.

The Optimal Solution to Ensure the Excellent

Certification Quality of EMI Testing


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3GHz Spectrum Analyzers have become an important

tool to characterize the EMI testing

In terms of propagating path, there classify into

conducted EMI and radiated EMI. The conducted EMI

results from that the radiated signal adheres along the

power line and hard to detect and recognize. Therefore, it

is necessary to build the causes and effects methodology

by way of the correct measurement to maintain the

electromagnetic compatibility, to target the

electromagnetic interference, and to detect radio

frequency interference. With the state-of-art design

among various testing devices, outstanding low noise

floor level of -117dBm at 1 GHz of the 3GHz spectrum

analyzer performs extreme sensitivity for picking up weak

signals.

Fig. 1. Using GKT-006 Probes for EMI Emission

Diagnosis Systems that have been well adopted for

EMC/EMI pre-test of electronic product before delivering

to EMI certification Lab, for example.

Along with a transports along other electronic devices or

component. And the radiated EMI caused by the

unwanted signal of harmonics generated from the system

case, antenna or electronic component transmits as a

electromagnetic wave to distort other electronic systems.

With the advancement of high-tech development, the

issues of EMI come out and diffuse over the broad

electronic applications. The increasing operating speed

and integrated density semiconductor devices are

enlarging the higher noise level than before so that many

of the distortion sources of signal become hard to detect

and recognize. Therefore, it is necessary to build the

causes and effects methodology by way of the correct

measurement to maintain the electromagnetic

compatibility, to target the electromagnetic interference,

and to detect radio frequency interference.

With the state-of-art design among various testing

devices, outstanding low noise floor level of -117dBm at 1

GHz of the 3GHz spectrum analyzer performs extreme

sensitivity for picking up weak signals. Along with a

20dB-gain preamplifier, the 3GHz spectrum analyzer can

further reach an equivalent noise floor level as low as

-137dBm, widely extending the measurement range. The

transient signal optimization on this spectrum analyzer

enables measurement of the power in rapid grasping the

EMI sources. These capabilities make the 3GHz spectrum

analyzer uniquely suited to solving today’s EMI problems.

The requirements of Electromagnetic compliance testing

has become the key indicator to forecast the market

potential for 3GHz Spectrum Analyzer

Electromagnetic compliance (EMC) remains a hot topic

among regulatory groups and manufacturers. With the

continued integration of electronics in consumer devices,

there will be a significant increase in the number of

possible electromagnetic sources present in any given

environment. EMC testing, therefore, is necessary to

guarantee the safe and effective operation of such

products. To combat the risks associated with


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electromagnetic interference (EMI), product

manufacturers are adopting spectrum analyzers as

reliable tools for EMC testing. Typically lightweight and

feature-rich, spectrum analyzers can be used in

conjunction with antennas, line impedance stabilization

networks (LISNs), and near-field probes to find EMI

radiation sources. The use of spectrum analyzers often

saves time and money for engineers who do not wish to

travel to an EMC lab for their compliance tests. Spectrum

analyzers that can handle an 3~20GHz frequency range

are well suited for examining satellite communications

systems’ operations, testing communications equipment,

and fulfilling wireless system commissioning and

troubleshooting. The communications industry is

perhaps the most important area of growth for spectrum

analyzers, as this sector continues to witness the

deployment of new wireless networks and standards that

must be tested for EMI. As technologies such as WiMAX,

3G wireless, and WCDMA continue to evolve, they are

expected to contribute a significant proportion of

revenues to the overall spectrum-analyzer market.

Although spectrum analyzers have been known for their

somewhat hefty price tag in the past, the introduction of

lower- cost testers has made such devices more

affordable and desirable to many end users. This is

largely attributed to vendors who have moved toward the

development of less-expensive handheld devices.

Fig. 2. There is a wide range of human risk associated

with electromagnetic interference

With their small footprints and portable nature, such

products allow for utility both in the field and on the

bench. Despite the increased use of handheld devices,

spectrum-analyzer vendors must realize that their

revenues may be hindered by the availability of previously

used systems currently in the market, which are prime

options for R&D engineers who wish to minimize

operating costs. Even with used systems available, the

mature spectrum analyzer market will continue to

experience modest growth, given its importance in EMC

testing. There depicts market revenues from 2003 to 2007

and expected revenues for 2008 in Fig.2. With a high

degree of market competition and price sensitivity,

vendors must understand the importance of developing

products with enough features and capabilities to satisfy

the testing needs of end users.

EMI Measurement Overview

With a compact spectrum analyzer, the manufacturers

making electronic products can easily build up the

production line for EMI testing or electronic system

designer can have the technical capability to develop the

high the capacity have been adopted by way of radiated

EMI ad Conducted EMI. For a formal EMI certification

test, in either an EMI chamber or an open field site, the

receiving antenna will pick up the emissions with in a

distance of 8 or 10 meters. This means the emissions may

come from anywhere within the DUT. The antenna will

receive them all the emissions, they can come from the

top, bottom, right or left hand side.

Fig. 3. EMI testing in Open side.


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In Fig.3, the DUT is placed on a rotatable table, the

receiving antenna is located 10 meters from the DUT, and

its stature is adjustable. The antenna output is connected

to a spectrum analyzer which is located in a shielded

room. A perfect Ground is needed to ensure an isolated

environment. During the measurement, the table will

rotate 360 degrees, so that the antenna can receive the

omni directional emissions. The antenna is also vertically

adjustable to catch the upward emissions. However, the

EMI testing results can not distinguish where on the DUT

the emissions were generated. When the emissions are

too strong and fail to pass regulations, the source needs

to be suppressed and thus have to be identified first. The

near field probe is used to find the source of emissions on

the DUT.

Fig. 4. Moving the probe around the DUT

The GKT-006 is a near field probe set which is used to

connect to a spectrum analyzer (in most of cases) to

detect the E or H field. The detection is done by holding

the probe and moving it around the DUT as shown in

Fig.4. When the probe is moved to the vicinity of the

source, the E/H field will be inducted through the probe,

showing the measured strength on the spectrum

analyzer. The emission source can be located accordingly.

During the operation, the probes (two loop and one stub

probe) are used by means of “non-direct touch” so the

probes will induct the E/H field. The probes are insulated

with plastic so that short circuits to the DUT are avoided.

Different types of probes are chosen to fit different

frequencies and DUT shapes. The tip probe is a direct

touch probe which allows the probe tip to directly test the

circuits. Even though there is no ground connection to

the probe the FR signal can still be measured for spot

testing and location measuring.

A Spectrum analyzer is the most widely used instrument

for EMI emission measurements. A spectrum analyzer

provides the frequency and strength information of

signals. With the use of a moving probe the source

location of emissions can be found rapidly. For diagnostic

purposes, it is recommended that our spectrum analyzer

is used in the “Peak Hold” trace mode to record

emissions. If emissions are weak, an additional

preamplifier can be used for amplifying emissions for

measurement. Besides, the 3GHz spectrum analyzer can

be an automatic test instrument instead of external

computer control. Users can define their own macros

through keypad on the front panel and store them into

sequence sets at most. Each sequence including pause

steps, which can be paused at the instant while observing

the measurement result. The quick EMI pretest can be

implemented on spectrum analyzer with EMI filter.

Fig. 5. The typical 3GHz Spectrum Analyzer


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Fig. 6. The main tool of EMI diagnostic package

Fig. 7. The EMI-specific software installed in EMI

diagnostic package

Interfaces and Connections of EMI Measurement

The probes have different connector types due to their

characteristics. When a probe is connected to a spectrum

analyzer, a suitable adapter is needed. Possible

connections are as follows.

1. When the loop probes ANT-01, ANT-02 and ANT-03

are connected to a spectrum analyzer, an N to BNC

adapter (ADP-01) is needed because these probes

are BNC type connectors. The cable used in the

GKT-006 is a test lead with BNC connectors at both

ends.

2. One can use probe detector PR-03 to point out and

track the conduction properties of electrical circuit by

the configuration as shown in Fig.9. This connection is

well performed on spectrum analyzer instead of the

oscilloscope that can’t activate the RF detection kit

without 50Ω input impedance.

Fig. 8. BNC probe Connections is well-posed with RF

cable and loop probes ANT-01, ANT-02 and ANT-03,

which enable to measure the background noise of

peripheral signal from TV or radio.

Fig. 9. Correct connections is well-posed with SMA cable

and probe detector PR-03 to track the circuit conduction

In terms of a spectrum analyzer set-up, we shall have the

primary setting of frequency range by scanning two zones,

30MHz~300MHz and 300MHz~1GHz under 120KHz of


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RBW setting. At first, enter the function key ”Trace” and

select “Peak” to pick out the main sources of largest

noise level by sequence as “Trace” then “More” then

“Detection”. In terms of the further advanced test, we

can choose the major source of noise peak120MHz, for

example. Assign the center frequency as this noise

peak120MHz and set the frequency span to 4MHz. Then

select “Detection”, then enter ”Q Peak”, and use “AVG”

to pick out the maximum and average value which will be

the practical way.

Example 1. Quickly checking the conduction properties of

electrical circuit

Fig. 10. Optimal solution of EMI emission Measurement

As shown in Fig.10, applying kits of loop probes to

proceed in simple tracking the EMI characteristics will

make it possible to save much more time in testing site

of production line. There are kits including ANT-01, BNC

cable, ADP-01 and a 10dB pre-amplifier GAP-802 to

capture the EMI emission source in this figure.

Example 2. The Pre-test Measurement for the Advanced

Test on the Process Equipments in Semiconductor

Manufacturing Sector

To attain the highly precision in robot movement along

the process chambers on equipment is significantly

affected by the normal programmable operation. And the

preventive maintenances of the equipment often spent

much time and efforts while going for the preliminary

check with conducted EMI calibration as shown in

Fig.11.[1]

Fig. 11. It takes much time for certification connection for

normal conducted EMI, which can cost-efficiently adopt

the pre-test measurement by simple EMI emission

detection.

The profound influence Pre-test by Spectrum analyzer

Measurement System on Conducted EMI certification

The noise sources can be decomposed into common

mode noise and differential mode noise. These two

components of noise sources are respectively caused by

their associated current. The noise can be extracted from

the line impedance stabilization network (LISN), shown in

Fig.12, the measured value after feed through noise

separator can be acquired by spectrum analyzer. With a

EMI detection bundled on a 3GHz spectrum analyzer,

Either involving the commitments of EMI detection or

simply build the easy connection may allow you to get rid

of most of the EMI troublesome.


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Fig. 12. Measurement system for Conducted EMI.

As an approach to killer application, 3GHz spectrum

analyzer inherits the advantages if high performance,

affordable cost, easy to use and light-weight portability.

Moreover, its extremely low noise floor greatly increases

the measurement range, advanced user interface brings

users with significant visual enhancement, and versatile

powerful functions make measurements simple and

accurate. The 3GHz spectrum analyzers have been offers

with the greatest performance-to-price ratio in the

market. Using the 3GHz spectrum analyzer as a

EMI/EMC pre-test measurement tool will likely eliminate

the possibility of measurement algorithm errors after

addressing the EMI testing in certification lab. The

leadership of 3GHz spectrum analyzer in delivering the

test industry’s first dedicated EMI measurement suite has

given it rapid adoption by a wide range of EMI/EMC

certification. There is a very good chance that one’s

electronic product will successfully undergo EMI/EMC

certification test with the 3GHz spectrum analyzer

making many of the measurements. If an issue does arise

during the EMI/EMC test, having the easily

portable single box SA available provides a means to

quickly troubleshoot circuits. The 3GHz spectrum

analyzer can help the engineer rescue the EMI/EMC effort

by rapidly identifying the issues. This can prevent the

lengthy setbacks that can occur with outdated and

inefficient test equipment.

References

[1] A, Krusubthaworn, R. Sivaratana, V. Ungvichian, A.

Siritaratiwat., Testing parameters of TMR heads affected

by dynamic-tester induced EMI, Journal of Magnetism

and Magnetic Materials 316(2007) e142-e144.

DUT

Spectrum Analyzer


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981028 The optimal solution to ensure the excellent ...g...The optimal solution to ensure the excellent certification quality of EMI testing 4 GOOD WILL INSTRUMENT CO., LTD. In Fig.3,